Source- Science News Online 

12/17/05  

Gene Linked to Skin Color

Scientists at Penn State College of Medicine in Hershey , PA , tracked down a gene that might play a role in determining a person’s skin color. The gene was originally found in golden fish that have honey-colored stripes instead of the typical black stripes. Dr. Cheng and his team identified a mutation in the gene in the unusual golden fish.  The team explored the possibility of that gene being involved in humans. They studied data generated by the Human Genome Project and found a comparable gene, which they called SLC24A5, located on human chromosome 15. This gene had a slightly different form in people of African heritage than in people of European descent.  The group, later, examined the genomes and skin color of 308 people of mixed African and European ancestries. Again, individuals with less of the pigment melanin (which would result in a lighter skin color) tended to have the European form of the gene.  Dr. Cheng cautions that this gene is not the only factor that plays a role in skin color.  These studies were published in the prestigious journal, Science. 

Source- Nature Online 

(Proc. Natl. Acad. Sci. USA 102, 16368-16373, 2005)

11/15/05  

Detecting Cancer Genes Early

Scientists have been searching for mutant DNA in a study of people with colorectal cancer. The detection was done on blood plasma of 33 patients with colorectal tumors and 10 without the tumor. Results show that even low levels of mutant DNA from cancerous cells can be detected by the technique. The technique is a sequencing assay developed by Bert Vogelstein of the Johns Hopkins Medical Institution in Baltimore, Maryland. The researches propose that the mutant DNA is released into the blood when cancerous cells are taken up by immune cells.

Source- Nature Online  

10/17/05  

Duplicate Genes Helps as a Backup

Sometimes identical genes remain in an organism instead of being deleted or inactivated.

Scientists in Switzerland used computer modeling and quantitative biochemical experiments to investigate families with duplicated genes in the yeast Saccharomyces cerevisiae. They found that extra genes can be used either as a backup, develop a new function, is under different regulation or increase the protein level encoded by that particular gene. All these mechanisms are equally important in the survival of duplicated or extra genes.

Source- Yahoo Science News

(Paper published in PNAS)

10/16/05  

A Gene Variant Affecting Sleep

Scientists at the University of Zurich have identified a gene variation that affect sleeping.

Animal studies show that genes control sleep intensity. The researchers focused on adenosine neurotransmitter system in the brain and isolated the gene that regulates the adenosine which acts on specific receptors that promotes sleep. Chemicals, such as caffeine, increase alertness.

High amount of adenosine makes people sleepy. According to Landolt, "it was shown in cat and rat studies that the concentration of adenosine increased locally in the basal forebrain with increasing duration of wakefulness. Whether it holds true in humans is not known."

Landolt evaluated 32 people and found that those with a gene variant involving a reduced metabolism of adenosine, slept more deeply than those who did not have the variant. This means that the variant contributed to the brain's electrical activity during sleep and wakefulness.

The study, Landolt said, indicated that adenosine plays a direct role in people's sleep quality. These genetic differences, he said, contribute to the variability in brain electrical activity during sleep and wakefulness.

The study is promising for developing a therapeutic drug that will help those who have problems sleeping.